Data Rate Limits

Nyquist Bit Rate (Noiseless Channel)

Theoretical maximum bit rate as

$$ \text{BitRate} = 2 \times \text{bandwidth} \times \log_2{L} $$

• $\text{bandwidth}$ is the bandwidth of the channel
• $L$ is the number of signal levels
• $\text{BitRate}$ is the bit rate in bits per seconds

Shannon Capacity (Noisy Channel)

Theoretical highest data rate for a noisy channel:

$$ \text{capacity} = \text{bandwidth} \times \log_2{(1 + \text{SNR})} $$

• $\text{bandwidth}$ is the bandwidth of the channel
• $\text{SNR}$ is the signal-to-noise ratio
• $\text{capacity}$ is the capacity of the channel in bits per second

Using Both Limits

In practice, we use both methods to find the limits and signal levels.

• Shannon capacity gives the upper limit
• Nyquist formula tells how many signal levels are needed

Performance

An introduction to terms needed for future chapters when discussing the performance of a network.